1. Field of the Invention
This invention pertains to shoes, and more particularly to shoes suitable for outdoor walking and outsoles therefor.
2. Prior Art
Shoes intended for outdoor use have different construction requirements than those intended for indoor use. A primary difference is that outdoor shoes must have an outsole durable enough to last for a reasonable period of time on hard, outdoor surfaces, such as pavement. Indoor shoes, such as slippers, have no such requirement and, therefore, their outsoles can be constructed of a variety of soft, flexible materials. As a flexible outsole of the type found on slippers can readily conform to the foot as it moves, it is decidedly more comfortable than the more rigid outsoles found on outdoor shoes.
To provide a measure of flexibility to an outdoor shoe, U.S. Pat. No. 2,590,648 discloses a sandal comprised of three separate rigid sections joined by hinges. While this arrangement imparts some flexibility to what would otherwise be a rigid outsole, it does not permit stretching in the lengthwise direction and, as the outsole is preferably comprised of wood, it is probable that even with the hinged arrangment, the sandal is not very comfortable. A complex foot orthosis disclosing a similar hinged construction is disclosed in U.S. Pat. No. 4,628,936.
Another arrangement for improving the flexibility of an outdoor shoe is disclosed in U.S. Pat. No. 2,362,010 wherein the toe part of the shoe is joined to the heel part by an adjustable tongue and tape for allowing relative flexing motion between the toe and heel parts, and also for accommodating adjustments to the length of the shoe. However, once the length is adjusted, the distance between the toe and heel parts is fixed and, as a consequence, the outsole does not accommodate lengthwise stretching.
U.S. Pat. No. 3,086,301 discloses an outdoor shoe having an outsole defining a cut-out in the ball area, which cut-out is covered by a sheet of relatively flexible material. While this arrangement purports to increase the flexibility of the outsole and therefore the comfort thereof, it likewise does not accommodate stretching in the lengthwise direction. A somewhat similar construction incorporated, however, in the insole of a shoe, is disclosed in U.S. Pat. No. 1,607,896.
U.S. Pat. No. 1,390,698 discloses an athletic shoe incorporating a flexible shank section joined at its ends to relatively stiff toe and heel pieces, and joined to the upper by stitching. While this structure accommodate flexing at the shank, it too does not accommodate stretching in the lengthwise direction both because the shank is merely flexible, not elastic, and also because the stitching joining the shank to the upper would, in any event, block lengthwise stretching.
In indoor shoes, such as slippers, where there is no requirement for a durable outsole, and therefore construction requirements are greatly simplified, elastic shanks have been proposed. For example, such an arrangement is disclosed in U.S. Pat. No. 2,252,315 wherein an elastic shank is joined between a vamp and a heel or counter-portion, as by stitching. Because the front and rear outsole portions are formed of a flexible material, the assembly of such a shoe poses no construction problems, but, of course, the shoe cannot be worn outside, lest the outsole portions rapidly wear through. Another stretchable slipper is disclosed in U.S. Pat. No. 4,554,749 wherein the entire upper is comprised of an elastomeric fabric in which forward and rearward inner sole and outer sole sections are stitched, such that the natural elasticity of the upper, in the vicinity between the front and rear inner and outer sole sections, can stretch. Again, this construction is unsuitable for outdoor use, lest the front and rear outsole sections wear through. It also requires that the entire upper be comprised of an elastomeric material, which is not always desirable.
It is therefore an object of the present invention to provide an improved shoe suitable for outdoor wear which accommodates lengthwise stretching.
It is a further object of the invention to provide an improved outsole suitable for incorporation in the shoe of the present invention.
It is yet a further object of the present invention to provide front and rear outsole portions suitable for fabricating the outsole of the invention.